This invention relates to a sensor for detecting the of cross wind on a vehicle.
When driving through a gust of cross wind, a vehicle without steering correction is laterally displaced and turned out of the wind to at least some extent. As a result, the vehicle experiences a steady-state course deviation upon emerging from the gust, into an area which is free of cross winds. In addition to the wind force and the direction of the wind relative to the driving direction of the vehicle, the driving speed of the vehicle and its geometry influence the extent of the lateral displacement and change of direction, which therefore differ from one vehicle to the next.
As a rule, the influence of the cross-wind on a vehicle is taken into account in its construction, and is kept as low as possible by appropriate design measures. However, for physical reasons, it is not possible to eliminate completely the influence of cross wind on the vehicle handling by passive design measures alone.
It has therefore been attempted to further reduce the influence of cross winds on vehicle handling by the use of sensors to detect cross winds, with either an axle of the vehicle or the steering angle of the wheels of the axle being adjusted in a manner calculated to compensate for the effect of cross winds.
German Patent Document DE-PS 11 08 091 discloses an arrangement which operates in this manner. By way of one pressure measuring point situated respectively on each side of the vehicle, pneumatic pipes lead to chambers on both sides of a diaphragm of a pneumatic control element. The pneumatic control element actuates a hydraulic valve which controls a final control element. In a first embodiment, the final control element with a spring loaded center position, displaces the suspension points of an axle of the vehicle relative to the vehicle body; in a second embodiment, it adjusts the steering angle of the wheels of this axle.
However, in this known arrangement, the effect of the pressure difference on the steering angle is fixed in advance (largely proportional to the pressure difference), and therefore does not optimize the handling dynamics of the vehicle. Likewise, any disturbance in the approaching air has a direct effect on the steering angle.
In German Patent Document DE 38 16 057 C1, an arrangement is disclosed for determining the influences of cross winds on a vehicle. A total of six manometric capsules are arranged on the vehicle, whose pressure values are linked to one another in an expensive manner. Such linking of the pressure values requires relatively high computing expenditures. Since absolute pressure values are required, all sensors must be connected on one side with a reference pressure chamber which is itself connected with the atmosphere by way of a throttle line, in order to be able to use less expensive differential pressure sensors.
It is an object of the present invention to provide a sensor for detecting influences of cross winds on the handling of a vehicle, which by means of relatively low expenditures with respect to measurement techniques can determine the influence of the cross wind on the vehicle and is capable of generating a quantity which can easily be processed by means of control units connected to it.
This object is achieved by the detection arrangement according to the invention, which requires only a single differential pressure sensor for detecting the influence of the cross wind (that is, the transverse force of the wind) on the vehicle. The sensor is connected with two pressure measuring points on the vehicle body by way of hoses or lines which, if possible, should have the same length. The pressure measuring points are situated symmetrically with respect to the vertically extending longitudinal plane of the vehicle on its forward portion, for example, on the front fenders. They are placed in an area of the outer skin of the vehicle body which is free of turbulences and from which, even under unfavorable approach flow conditions, the flow does not separate. The sensor detects the vehicle's entry into or emergence from a gust of cross wind in that the detected values of the differential pressure are exponentially smoothed, and, from the respective difference of two successively detected values of the smoothed differential pressure, a rising or a falling of the differential pressure is determined.
The principal advantages of the invention are that a sensor for detecting the influences of cross wind on the vehicle is provided which requires only relatively low expenditures with respect to measurement techniques. In addition, the sensor generates easily processable output values which may, for example, by used in a control unit connected downstream for the control of a steering element of the vehicle as a function of the cross wind influence.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.